Medical infusion pumps may be designed to be carried by a user, to a large extent, continuously and concealed from view. In some embodiments, the medical infusion pump may have a size of about a cigarette packet or less and be designed to be carried in a belt holster, in a trouser's pocket, in a necklace-like way, or the like. In addition, such medical infusion pumps are designed to be coupled with a subcutaneous infusion cannula via a tubing of, e.g., 0.3 m to 1.5 m length. In other embodiments, a medical infusion pump may include a subcutaneous infusion cannula and be adhesively attached directly to the skin of a patient at the infusion site.
Some medical infusion pumps may be designed to infuse medicine in accordance with a quasi-continuous and time-variable infusion profile. Such infusion pumps may be used, for example in the therapy of diabetes mellitus by quasi-continuous subcutaneous insulin infusion, CSII. In CSII therapy, insulin is subcutaneously infused into a diabetic's body in accordance with the diabetic's personal and time-varying basal insulin demands. Such an infusion pump may further be designed to infuse additional medicine insulin boli on demand, for example insulin boli to cover the intake of carbohydrate-comprising meals.
Medical devices like medical infusion pumps are typically powered by an electrical power source, typically a rechargeable or non-rechargeable battery, such as a common AA or AAA cell or a special-purpose power pack. The medical infusion pump typically comprises a housing with a user-accessible compartment or interface for holding or attaching the power source in a replaceable way. Those devices typically further comprise at least one processor, for example in form of an ASIC or microcontroller, which controls the device operation.
A failure occurs if the voltage provided by the power source to the medical device or specific components within the medical device drops to a critical value. The critical value is also called a reset voltage level because further operation is not possible and a reset of the medical device or a specific component within the medical device, in particular the processor, is performed at this voltage level. This results in the device stopping, at least temporarily, intended operations. For a medical infusion pump, this means typically terminating infusion. In some cases, the user, for example a diabetic, may not even become immediately aware of this potentially dangerous situation.
For liability reasons as well as for general failure and complaint-analysis-purposes, it is of considerable value to know if the reason for an interruption of the power supply was either a misuse of the device by the user such as, for example, removing the power source during normal operation or dropping of the device, or a problem within the medical device such as, for example, within the power source itself.